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iOS教程
iOS (iPhone, iPad)教程
IOS - 快速入门
IOS - 开发环境配置
iOS - Objective-C基础
iOS - 创建第一个
IOS - 动作和插座
iOS - Delegates实例
iOS - UI元素
iOS - Accelerometer(加
IOS - 通用应用程序
IOS - 摄像头管理
iOS - 位置处理
iOS - SQLite 数据库
iOS - 发送电子邮箱
iOS - 音频和视频
IOS - 文件处理
IOS - 访问地图
iOS - 应用程序内购买
iOS - iAd 整合
 
 

iOS - SQLite 数据库
100 次浏览
21次
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简介

sqlite 可用于在 IOS 处理数据。只是使用 sqlite 的查询,这使得它更容易为那些熟悉 SQL 查询开发人员使用。

涉及的步骤

1. 创建一个简单的 View based application

2. 选择项目文件,然后选择“目标”,选择框架添加libsqlite3.dylib库

3. 现在创建一个新的文件,通过选择 File-> New -> File... -> select Objective-C 类并点击“next"

4. 类命名为 DBManager 并作为 NSObject 的子类

5. 选择“创建”.

6. 现在更新 DBManager.h 如下

#import <Foundation/Foundation.h>
#import <sqlite3.h>

@interface DBManager : NSObject
{
NSString *databasePath;
}

+(DBManager*)getSharedInstance;
-(BOOL)createDB;
-(BOOL) saveData:(NSString*)registerNumber name:(NSString*)name
department:(NSString*)department year:(NSString*)year;
-(NSArray*) findByRegisterNumber:(NSString*)registerNumber;

@end

7. 现在更新DBManager.m 如下

#import "DBManager.h"
static DBManager *sharedInstance = nil;
static sqlite3 *database = nil;
static sqlite3_stmt *statement = nil;

@implementation DBManager

+(DBManager*)getSharedInstance{
if (!sharedInstance) {
sharedInstance = [[super allocWithZone:NULL]init];
[sharedInstance createDB];
}
return sharedInstance;
}

-(BOOL)createDB{
NSString *docsDir;
NSArray *dirPaths;
// Get the documents directory
dirPaths = NSSearchPathForDirectoriesInDomains
(NSDocumentDirectory, NSUserDomainMask, YES);
docsDir = dirPaths[0];
// Build the path to the database file
databasePath = [[NSString alloc] initWithString:
[docsDir stringByAppendingPathComponent: @"student.db"]];
BOOL isSuccess = YES;
NSFileManager *filemgr = [NSFileManager defaultManager];
if ([filemgr fileExistsAtPath: databasePath ] == NO)
{
const char *dbpath = [databasePath UTF8String];
if (sqlite3_open(dbpath, &database) == SQLITE_OK)
{
char *errMsg;
const char *sql_stmt =
"create table if not exists studentsDetail (regno integer
primary key, name text, department text, year text)";
if (sqlite3_exec(database, sql_stmt, NULL, NULL, &errMsg)
!= SQLITE_OK)
{
isSuccess = NO;
NSLog(@"Failed to create table");
}
sqlite3_close(database);
return isSuccess;
}
else {
isSuccess = NO;
NSLog(@"Failed to open/create database");
}
}
return isSuccess;
}

- (BOOL) saveData:(NSString*)registerNumber name:(NSString*)name
department:(NSString*)department year:(NSString*)year;
{
const char *dbpath = [databasePath UTF8String];
if (sqlite3_open(dbpath, &database) == SQLITE_OK)
{
NSString *insertSQL = [NSString stringWithFormat:@"insert into
studentsDetail (regno,name, department, year) values
("%d","%@", "%@", "%@")",[registerNumber integerValue],
name, department, year];
const char *insert_stmt = [insertSQL UTF8String];
sqlite3_prepare_v2(database, insert_stmt,-1, &statement, NULL);
if (sqlite3_step(statement) == SQLITE_DONE)
{
return YES;
}
else {
return NO;
}
sqlite3_reset(statement);
}
return NO;
}

- (NSArray*) findByRegisterNumber:(NSString*)registerNumber
{
const char *dbpath = [databasePath UTF8String];
if (sqlite3_open(dbpath, &database) == SQLITE_OK)
{
NSString *querySQL = [NSString stringWithFormat:
@"select name, department, year from studentsDetail where
regno="%@"",registerNumber];
const char *query_stmt = [querySQL UTF8String];
NSMutableArray *resultArray = [[NSMutableArray alloc]init];
if (sqlite3_prepare_v2(database,
query_stmt, -1, &statement, NULL) == SQLITE_OK)
{
if (sqlite3_step(statement) == SQLITE_ROW)
{
NSString *name = [[NSString alloc] initWithUTF8String:
(const char *) sqlite3_column_text(statement, 0)];
[resultArray addObject:name];
NSString *department = [[NSString alloc] initWithUTF8String:
(const char *) sqlite3_column_text(statement, 1)];
[resultArray addObject:department];
NSString *year = [[NSString alloc]initWithUTF8String:
(const char *) sqlite3_column_text(statement, 2)];
[resultArray addObject:year];
return resultArray;
}
else{
NSLog(@"Not found");
return nil;
}
sqlite3_reset(statement);
}
}
return nil;
}

8. 更新ViewController.xib文件如下。

9. 为上述文本字段创建IBOutlets

10. 为上述按钮创建IBAction

11. 更新ViewController.h 如下:

#import <UIKit/UIKit.h>
#import "DBManager.h"

@interface ViewController : UIViewController<UITextFieldDelegate>
{
IBOutlet UITextField *regNoTextField;
IBOutlet UITextField *nameTextField;
IBOutlet UITextField *departmentTextField;
IBOutlet UITextField *yearTextField;
IBOutlet UITextField *findByRegisterNumberTextField;
IBOutlet UIScrollView *myScrollView;
}

-(IBAction)saveData:(id)sender;
-(IBAction)findData:(id)sender;

@end

12. 更新 ViewController.m 如下

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)
nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

-(IBAction)saveData:(id)sender{
BOOL success = NO;
NSString *alertString = @"Data Insertion failed";
if (regNoTextField.text.length>0 &&nameTextField.text.length>0 &&
departmentTextField.text.length>0 &&yearTextField.text.length>0 )
{
success = [[DBManager getSharedInstance]saveData:
regNoTextField.text name:nameTextField.text department:
departmentTextField.text year:yearTextField.text];
}
else{
alertString = @"Enter all fields";
}
if (success == NO) {
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:
alertString message:nil
delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
}
}

-(IBAction)findData:(id)sender{
NSArray *data = [[DBManager getSharedInstance]findByRegisterNumber:
findByRegisterNumberTextField.text];
if (data == nil) {
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:
@"Data not found" message:nil delegate:nil cancelButtonTitle:
@"OK" otherButtonTitles:nil];
[alert show];
regNoTextField.text = @"";
nameTextField.text =@"";
departmentTextField.text = @"";
yearTextField.text =@"";
}
else{
regNoTextField.text = findByRegisterNumberTextField.text;
nameTextField.text =[data objectAtIndex:0];
departmentTextField.text = [data objectAtIndex:1];
yearTextField.text =[data objectAtIndex:2];
}
}

#pragma mark - Text field delegate
-(void)textFieldDidBeginEditing:(UITextField *)textField{
[myScrollView setFrame:CGRectMake(10, 50, 300, 200)];
[myScrollView setContentSize:CGSizeMake(300, 350)];
}
-(void)textFieldDidEndEditing:(UITextField *)textField{
[myScrollView setFrame:CGRectMake(10, 50, 300, 350)];

}
-(BOOL) textFieldShouldReturn:(UITextField *)textField{

[textField resignFirstResponder];
return YES;
}
@end

输出

现在,当我们运行应用程序时,我们会得到下面的输出,我们可以添加并发现学生的详细信息


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100 次浏览
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